Phenylboronic acids (PBA) are known to bind sugars in an aqueous and organic media. 1 Based on the PBA-sugar binding, many kinds of PBA derivatives whose absorption or emission spectra are sensitive to sugar have been synthesized for the spectroscopic determination of sugars. 2-4 These methods, however, rely on a homogeneous system in an aqueous or nonaqueous solution, where PBA derivatives are added in the sample solution as reagent. On the other hand, from the viewpoint of the development of sugar sensors, PBA derivatives should be immobilized on the surface of transducers. In this context, carbon and metal electrodes have been modified with PBA-containing polymers such as poly(acrylate), 5 poly(aniline), 6 and poly(pyrrole). 7 Self-assembled monolayers of PBA have also been used for developing electrochemical and optical sugar sensors. [8][9][10] We report here a preliminary result on the voltammetric response of PBA monolayer-modified Au electrode to glucose, mannose, and fructose. The peak current in the cyclic voltammogram was found to be sensitive to the adsorption of sugars on the electrode surface. The data show that the PBA monolayer-modified Au electrode may be promising as an electrochemical sensor for sugar sensing.